СИСТЕМА:ПЕРЕМЕННЫЕ:var0:ЗНАЧЕНИЕ
sys.var0.varValue.ToString()
var0.varValue >= var1.varValue
sys.var0

string a = "";
        string b = "";
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
             txtResult.Text = Refactor(txtSrc.Text,txtOld.Text, txtNew.Text);
        }

        public string MatchEvaluatorMethod(Match match)
        {
            return match.ToString().Replace(a, b);
        }

        public string Refactor(string src, string oldName, string newName)
        {
            string pattern_ = @"(\W|^)" +oldName +@"(\W|$)";
            a = oldName;
            b = newName;
            Regex reg_ = new Regex(pattern_);
            return Regex.Replace(src, pattern_, new MatchEvaluator(MatchEvaluatorMethod));
        }

public string Refactor(string src, string oldName, string newName)
        {
            string pattern_ = @"(\W|^)(" + oldName + @")(\W|$)";
            Regex reg_ = new Regex(pattern_);
            string replc_ = @"$1"+newName+"$3";
            return reg_.Replace(src, replc_);
        }